[RESOLVED] Select socket call crashes

[dreamz_dollar]

Hi,
Can somebody help me in knowing in what cases select call can crash.

If file descriptor being set in FD_SET is -1, the FD_SET crahses, i observed that .
In case, select call has a Read FD list conatining a FD which is invalid i.e -1, the select call doesnt crash but returns an error -1.

What can be other causes for select crash?

Thanks

[sreehari]

Use GetLastError ()to find the exact cause of the error.

[dreamz_dollar]

GetLasterror() would be useful only if select returns without crashing.Program exits from select itself.
The Program crashes at select call and its during load testing.So i need to know possible crash causes for select...

To give an idea abt it...the backtrace looks like this:

/lib/libc.so.6(__select+0x61)[0x41d79b91]

/lib/libc.so.6[0x41ce1ae0]

./dcm(_ZN17CMH323Gk_RAS_Impl14ReadThreadFuncEPv+0x30)[0x87fe0aa]

./dcm(_Z22our_own_thread_routinePv+0x277)[0x884d939]

/lib/libpthread.so.0[0x40017a4b]

/lib/libc.so.6(__clone+0x57)[0x41d7f5b7]

[0xb8bfec6c]

[0x10c1c]

[MikeAThon]

That's no help.

Post your code where you set up the fd_set's and then call select().

Are you using the macros FD_ZERO and FD_SET, to clear and then add your socket descriptor to the fd_set?

Which OS are your programming for?

Mike

[dreamz_dollar]

Find below the peice of code:

 int l_fd_read = m_pUdp_device_read->GetSocket();

   while (!m_ReadThread->ShouldQuit ())
   {
      // Watch RAS listening socket to see when it has input.
      FD_ZERO (&l_fd_set);

      FD_SET (l_fd_read, &l_fd_set);

      // Wait up to 100 milliseconds.
      l_timeval.tv_sec = 0;
      l_timeval.tv_usec = 100000;

      int l_iRetval = select (l_fd_read + 1, &l_fd_set, 0, 0, &l_timeval);

      if (m_ReadThread->ShouldQuit ())
      {
         MLogError("GK_RAS_IF: ShouldQuit() from udp socket\n");
         break;
      }

      if (l_iRetval > 0)
      {
         if (FD_ISSET (l_fd_read, &l_fd_set))
         {
            int l_iBytesRead = m_pUdp_device_read->Read (l_caUdpReadBuffer,
                                                         sizeof (l_caUdpReadBuffer));
            if (l_iBytesRead > 0)
            {
               // got something
               ProcessIncomingMessage (l_caUdpReadBuffer, l_iBytesRead);
            }
            else if (l_iBytesRead ==  0)
            {
               ;
            }
            else // l_iBytesRead < 0
            {
               MLogError("GK_RAS_IF: failed to read from udp socket\n");
               break;
            }
         }
      }

See this code works fine, normally but crashes sometimes on running a call load test.

My analysis:
This select call is being done in a thread.
There is a separate thread which closes the socket in FD list of select call sometimes and sets the FD = -1.
But i have a tried a test program in which i set FD = -1, but select doesn't crash in that, just returns -1.
Though FD_SET crashes..



So cant figure out why select should crash???

Any help is highly appreciated..

[MikeAThon]

Is your application multithreaded?

If so, then you need to synchronize access to the socket handle, so that the handle is not (for example) closed by one thread while it is still in use by another.

Mike

[uKER]

I have the exact same issue.
Calling select() crashes my program, no exception thrown, nothing.
I have no multithreaded access to the socket.
Did you ever solve this?
Any ideas will be appreciated.

[VictorN]

Wouldn't you like to post some code snippets?

[uKER]

Never mind. I feel like a total idiot.
An asynchronous condition was causing my main() function to return, meaning my program was ending as normally as it gets.
It just happens that it happened during the select()
Everything's good now.

Thanks nonetheless.